Theoretical And Experimental Researches On Polarization Maintaining Photonic Crystal Fibers

In this paper, the concepts of both photonic crystal and photonic crystal fiber arefirstly presented, and the features of photonic crystal fibers which are different fromthose of general fibers are introduced. Compared with conventional polarizationmaintaining fibers, polarization-maintaining photonic crystal fibers have manysuperior properties. After that, the research development of both polarizationmaintaining photonic crystal fibers and photonic crystal fibers made of multi-component glasses are discussed. Then the five common methods for theoreticallyanalyzing photonic crystal fibers are introduced, and the finite element method usedin this article is particularly recommended. Afterwards, a kind of photonic crystalfiber with two big air-holes, which is made of a kind of multi-component glass, isproposed, designed and drawn, and its main parameters are measured. Finally a sort ofphotonic crystal fiber with rectangular air-holes is proposed. The research contentsinclude:1. The finite element method is applied to design polarization maintaining photoniccrystal fiber with two big air-holes, which is based on the multi-component glass.Besides, the birefringence, and dispersion characteristics of this kind of fiber arestudied. From the numerical results, it can be found that the variation ofbirefringence with the changes of hole spacing, the diameter ratio of the big tosmall air-holes and the small air-holes diameter vs. the spacing ratio. Then thematerial dispersion, waveguide dispersion and chromatic dispersion of thedesigned fiber are calculated, thus, the wavelength where the dispersion is zero isconcluded.2. The designed photonic crystal fibers are drawn by using the capillary-stackingmethod, and it can be found that the experimental results are very good. By employing the microscope and scanning electron microscope, it can be observedthat the shape of the small air-holes is kept well even when the diameter of thesmall air-hole is0.6μm.3. The related parameters of the drawn fiber are measured, including the crosssection of the fiber, the refractive index distribution, single-mode feature, beatlength, polarization mode dispersion, group delay phase, polarization dependentloss, polarization extinction ratio, and so on. Then the theoretical andexperimental results of the beat length are compared, and the reasons for this areanalyzed.4. A kind of photonic crystal fiber with rectangular air-holes is proposed, and theirbirefringence and confinement loss properties are analyzed by employing thefinite element method. Besides, a modified capillary-stacking and drawing methodis proposed to fabricate this sort of fiber.